1. Field of the Invention
The present invention relates generally to medical methods and devices. In particular, the present invention relates to methods and devices for applying energy to the urethra to achieve volumetric tissue reduction.
A number of medical conditions affect the male urethra causing a variety of symptoms including painful or difficult urination, a swollen prostate, blood in the urine, lower back pain, and the like. Some of these conditions, such as prostatitis, are bacterial infections which can be treated with antibiotics and other drugs. Other conditions, however, such as benign prostatic hyperplasia (BPH) and prostatic carcinoma, result in enlargement of the prostate and obstruction of the urethra, sometimes leading to complete loss of bladder function.
Both BPH and prostatic cancer require treatments which remove or shrink tissue in the prostate surrounding the urethra. Common treatments include transurethral resection of the prostate (TURP) where a resectoscope is placed in the urethra and used to remove excess prostatic tissue. Another procedure, referred to as transurethral incision of the prostate (TUIP), relies on cutting muscle adjacent to the prostate to relax the bladder opening to relieve difficulty in urination. More recently, a procedure referred to as transurethral needle ablation (TUNA) has been introduced where a needle is advanced through the urethra into the prostate and used to deliver energy, such as microwave, radiofrequency, or ultrasound energy, to reduce the size of the prostate, again relieving pressure on the urethra. Laser ablation using transurethral optical fibers also finds use.
While generally successful, none of these methods are adequate to treat all patients and all conditions. In particular, patients having severe tissue intrusion into the urethral lumen resulting from BPH or prostatic cancer are difficult to treat with minimally invasive protocols which rely on tissue shrinkage rather than resection. Thus, many of these patients will eventually require conventional surgical resection.
For these reasons, it would be desirable to provide minimally invasive methods and devices which provide for enlarging the luminal area and/or volumetric resection of tissue surrounding the urethra. It would be particularly desirable if such methods and devices provided for removal or destruction of such tissues surrounding the urethra where the removal or destruction products can be removed from the lumen to relieve pressure on the urethra, even where large volumes of tissue have been removed. Alternatively or additionally, the methods and devices should provide for anchoring of the treatment device relative to the urethra in order to provide a stable platform for treatment protocols which do not require visualization. Methods and devices for performing such protocols should present minimal risk to the patient, should be relatively easy to perform by the treating physician, and should allow for alleviation of symptoms with minimal complications even in patients with severe disease. At least some of these objectives will be met by the inventions described below.
2. Description of the Background Art
Use of a transurethral endoscope for bipolar radiofrequency prostate vaporization is described in Boffo et al. (2001) J. Endourol. 15:313-316. Radiofrequency discharge in saline solutions to produce tissue-ablative plasmas is discussed in Woloszko et al. (2002) IEEE Trans. Plasma Sci. 30:1376-1383 and Stalder et al. (2001) Appl. Phys. Lett. 79:4503-4505. Air/water jets for resecting tissue are described in Jian and Jiajun (2001) Trans. ASME 246-248. US2005/0288639 described a needle injector on a catheter based system which can be anchored in a urethra by a balloon in the bladder. U.S. Pat. Nos. 6,890,332; 6,821,275; and 6,413,256 each describe catheters for producing an RF plasma for tissue ablation. Other patents and published applications of interest include: U.S. Pat. Nos. 7,015,253; 6,890,332; 6,821,275; 6,413,256; 6,378,525; 6,296,639; 6,231,591; 6,217,860; 6,200,573; 6,179,831; 6,142,991; 6,022,860; 5,994,362; 5,872,150; 5,861,002; 5,817,649; 5,770,603; 5,753,641; 5,672,171; 5,630,794; 5,562,703; 5,322,503; 5,116,615; 4,760,071; 4,636,505; 4,461,283; 4,386,080; 4,377,584; 4,239,776; 4,220,735; 4,097,578; 3,875,229; 3,847,988; US2002/0040220; US2001/0048942; WO 93/15664; and WO 92/10142.